The present invention relates generally to devices and methods for improving the function of a defective heart valve. The devices and methods disclosed herein are particularly well adapted for implantation in a patient's heart for reducing regurgitation through a heart valve.
The function of the heart may be seriously impaired if any of the heart valves are not functioning properly. The heart valves may lose their ability to close properly due to e.g. dilation of an annulus around the valve or a leaflet being flaccid causing a prolapsing leaflet. The leaflets may also have shrunk due to disease, e.g. rheumatic disease, and thereby leave a gap in the valve between the leaflets. The inability of the heart valve to close properly can cause a leak backwards (i.e., from the outflow to the inflow side), commonly referred to as regurgitation, through the valve. Heart valve regurgitation may seriously impair the function of the heart since more blood will have to be pumped through the regurgitating valve to maintain adequate circulation. Heart valve regurgitation decreases the efficiency of the heart, reduces blood circulation, and adds stress to the heart. In early stages, heart valve regurgitation leaves a person fatigued or short of breath. If left unchecked, the problem can lead to congestive heart failure, arrhythmias or death.
Regurgitation through the mitral valve, sometimes referred to as mitral insufficiency or incompetence, is a particularly common problem that affects the health of millions of adults. By some estimates, mitral valve regurgitation affects as many as one in five people over age 55. The mitral valve is positioned on the left side of the heart between the left atrium and left ventricle. The mitral valve comprises an annulus, anterior and posterior leaflets, and chordae for attaching the leaflets to papillary muscles. Changes in the geometric configurations of the left ventricle, papillary muscles and mitral annulus may adversely affect the function of the mitral valve and lead to regurgitation. Other factors such as disease, calcification, infection and injury may also cause mitral valve regurgitation.
Heart valve disease, such as mitral valve regurgitation, is typically treated by replacing or repairing the diseased valve during open-heart surgery. However, open-heart surgery is highly invasive and is therefore not an option for many patients. For high-risk patients, a less-invasive method for repair of heart valves is considered generally advantageous. In U.S. Pat. No. 6,210,432 to Solem et al., a less invasive method has been proposed for treating mitral insufficiency without the need for cardiopulmonary by-pass and opening of the chest and heart. The method uses a device comprising an elongate body having such dimensions as to be insertable into the coronary sinus, which is a vein that substantially encircles the mitral orifice and annulus and drains blood from the myocardium to the right atrium. The elongate body has two states, in a first of which the elongate body has a shape that is adaptable to the shape of the coronary sinus, and to the second of which the elongate body applies a compressive force along a posterior region of the mitral valve annulus. The compressive force applied to the mitral valve annulus pushes the mitral valve leaflets into closer proximity and reduces regurgitation. However, due to variations in the type of mitral valve disease and the location of the coronary sinus relative to the mitral valve annulus, this approach may not be suitable for all patients.
In another method, catheter-based procedures have been developed for treating the mitral valve using an “edge-to-edge” approach. In this approach, the free edges of the anterior and posterior mitral valve leaflets are attached along a central region to create a mitral valve having a double orifice. In one method developed by Edwards Lifesciences Corporation of Irvine, USA, an elongate catheter is advanced into the mitral valve for applying suture to the edges of the mitral valve leaflets. A clip is then advanced over the suture to secure the leaflet edges together. Although this “edge-to-edge” approach has shown great promise, similar to the coronary sinus implant, it has been found that this approach may not be suitable for all patients.
U.S. application Ser. No. 11/407,582 to Solem (hereinafter “the '582 application”), entitled “A Blood Flow Controlling Apparatus,” filed on Apr. 19, 2006, now Publication No. 2006/0241745, discloses a variety of devices and methods for treating heart valves using another less-invasive approach. In the '582 application, the contents of which are hereby incorporated by reference, preferred embodiments of blood flow controlling devices are described which are primarily configured for delivery into the heart via a percutaneous approach. As described in the '582 application, percutaneous methods of treating heart valves are often desirable, especially for high risk patients, because extracorporeal circulation is not required. However, there are conditions in which percutaneous procedures may not be appropriate. Accordingly, there is a need for new procedures for treating heart valves using minimally-invasive surgical techniques. It is preferable that such minimally-invasive surgical techniques be capable of treating heart valves without requiring extracorporeal circulation.
Accordingly, there is an urgent need for an alternative device and method of use for treating heart valve disease in a minimally invasive procedure that does not require extracorporeal circulation. It is desirable that embodiments of such a device and method be capable of reducing or eliminating regurgitation through a heart valve. It is also desirable that embodiments of such a device and method be well-suited for treating a mitral valve. It is also desirable that such a device be safe, reliable and easy to deliver. It is also desirable that embodiments of such a device and method be applicable for improving heart valve function for a wide variety of heart valve defects. It is also desirable that embodiments of such a device and method be capable of improving valve function without replacing the native valve. The present invention addresses this need.